1. Field
Exemplary embodiments of the invention relate to a thin film fabricating apparatus, an organic light emitting device using the same, and a method of manufacturing the organic light emitting device.
2. Description of the Related Art
An organic light emitting device (hereinafter referred to as an organic EL device) is a current-driving type of light emitting element using luminescence generated by recombining electrons and holes which are injected in an organic thin film in dual-faced electrodes, where the current-driving type of light emitting element is obtained by providing electrodes on both opposite surfaces of a thin film made of an organic material and applying a voltage between the facing electrodes to induce electrons and holes injected into the organic thin film to be recombined. As it may provide high luminescent brightness at a low voltage and high visibility, and may emit light by itself, the organic light emitting device has been actively researched for a light-weight and thin display.
The current method of manufacturing an organic thin film generally used for the organic light emitting device includes a dry process such as vacuum deposition and a wet process such as a spin coating. The dry process is a coating process using a relatively low molecular organic material and has characteristics of easily controlling a thickness, partitioning a coating region using a mask having appropriately-sized openings, and easily providing a structure of stacking organic materials having different properties. In the process, a “multi-layered technique” easily providing a stacking structure is particularly important. As the luminous efficiency and the device life-span of the organic light emitting device have remarkably improved, the organic light emitting device may be employed for many applications as a practicable display. However, as this technique requires a vacuum device, the current method has limitations of improving productivity and saving cost due to a high cost for initial introduction and maintenance of the device, as well as difficulty in using this technique for a large-sized substrate.
The wet process is applicable for a polymer material having excellent physical stability such as a coating property or heat resistance, and the apparatus is simple and does not require a specific atmosphere such as a vacuum, so the wet process is considered to be suitable for mass production and for manufacturing a low cost product. However, to accomplish the high efficiency and a long life span, it is important to provide a stacking structure using materials having different properties, but the wet process causes problems in that a solvent of an upper thin film material dissolves and is permeated into the lower organic material to delaminate the lower layer, so these problems need to be prevented. In order to solve the problems, additives such as a cross-linking hardener may be used, but the additives are known for inhibiting the light emitting property. Thereby, there are many difficulties in accomplishing a high performance multi-layer structure causing no loss of the device function.
There are several suggestions to apply an electro-spray method (hereinafter referred to as an ES method) to manufacturing an organic EL device due to a simple patterning. The ES method includes spraying a solution of a functional material while applying a high voltage between a conductive substrate and a nozzle discharging the solution to attach the same to the substrate. The electrified solution may be changed into fine liquid droplets having a nano-scale by mutual repulsion and dispersion, and the solvent is evaporated by rapidly increasing the surface area to attach only a solute (e.g., organic material) in the solution as a dried state onto the substrate to provide a uniform layer, to stack a plurality of layers.